植入用Ti-6Al-4V合金模拟体液浸泡后高频和超高周疲劳性能  

Ultra-high cycle fatigue behaviors of implanted Ti-6Al-4V in high frequency after subjection to simulated body fluid

作　　者：刘永杰[1] 欧阳巧琳 田仁慧[1] 王清远[1] 

机构地区：[1]四川大学力学科学与工程系,成都610065 [2]洛阳LYC轴承有限公司,洛阳471039

出　　处：《医用生物力学》2011年第1期7-12,共6页Journal of Medical Biomechanics

基　　金：国家杰出青年科学基金资助项目(10925211);国家自然科学基金资助项目(10772125)

摘　　要：目的为预测植入用Ti-6Al-4V钛合金的使用寿命,研究其在模拟体液浸泡后,107周次以后的超高周疲劳性能。方法将Ti-6Al-4V钛合金试样在模拟体液中分别浸泡2 d和6 d;利用超声疲劳实验技术,在室温下分别对这两组试样进行超高周疲劳性能测试;利用电子显微镜观察疲劳断口并对裂纹源进行X射线能谱分析,研究其裂纹萌生机理,并与未经浸泡的同种材料的超声疲劳性能进行对比分析。结果模拟体液浸泡后的材料的S-N曲线与未经浸泡时的趋势相近,在104～108周次范围内的疲劳寿命都呈连续下降状态,在107～108周次循环范围内曲线下降趋势有所变慢;模拟体液浸泡后的试样在107周次之前寿命下降更快,107周次之后模拟体液浸泡过的试样寿命比未处理的试样寿命低;浸泡6 d后的试样的寿命和浸泡2 d后的相差不大。疲劳循环超过107周次后,仍然发生疲劳断裂,并不存在传统意义上的疲劳极限。疲劳寿命108周次以后的试样疲劳裂纹在内部萌生,一般为铝元素聚集区;疲劳寿命107周次以前裂纹一般萌生于试件表面,有些试件出现了多处裂纹源。结论模拟体液浸泡会降低Ti-6Al-4V钛合金的超高周疲劳性能;随着循环周次的增加,裂纹萌生由试件表面向其内部转换。Objective To study the ultra-high cycle fatigue behaviors of the Ti-6Al-4V alloy implant after subjection to simulated body fluid（SBF） environment exceeding 107 cycles,and to predict its service life.Method The Ti-6Al-4V alloy specimens were subjected to SBF in two groups for two days and six days respectively;using the ul-trasonic fatigue testing technique,the ultra-high cycle fatigue properties of Ti-6Al-4V alloy after subjection to SBF in body temperature were studied and the initiation mechanisms of fatigue cracks were investigated and analyzed with scanning electron microscopy（SEM） and energy dispersive atomic X-ray（EDA X-ray）.Then,a compari-son with corresponding behaviors of the normal Ti-6Al-4V alloy was made.Results The S-N curve of the Ti-6Al-4V alloy after subjection had the similar tendency as that of the normal one,showing that they descended continu-ously during 104 and 108cycles and the descending tendency was lower in the region of 10^7～10^8 cycles;the life ofthe specimens after subjection dropped before the fatigue life of 107 cycles and was smaller after the fatigue life of107 cycles than that of the normal ones;the life of the specimens subjected for six days had little difference withthat subjected for two days;fracture could still occur beyond 10^7 cycles,showing that there was no fatigue limit asthe traditional fatigue conception described.Fatigue cracks mainly initiated from the surface of specimen beforethe fatigue life of 10^7 cycles and some specimens had multiple crack initiation sites;fatigue failure initiated from in-ternal inclusion where mostly the element Al aggregated after the fatigue life of 108cycles.Conclusions The ul-tra-high cycle fatigue properties of the Ti-6Al-4V alloy decreas a little with SBF subjection;the initiation site of thefatigue crack changes from the surface to the internal defect with the increase of the number of cycle.

关 键 词：钛合金 体液浸泡 疲劳测试 疲劳断口 S-N曲线 断裂力学 

分 类 号：R318.01[医药卫生—生物医学工程]